The frequency response differs (20 Hz-20,000 Hz vs 18 Hz -20000 Hz), which can influence how well the headphones reproduce lows, mids, and highs. In general, both options are suitable for everyday use including music, calls, travel, and work-from-home scenarios. Both headphones offer solid battery performance, making them suitable for long listening sessions and travel. Sennheiser HD-451 and Sennheiser HD 400S offer different noise cancellation capabilities (Yes vs AMBIENT), which can impact how effectively they block external noise. The driver size differs between the two (NA vs 9.7 mm), which can influence sound depth, bass response, and overall audio clarity. If you're comparing Sennheiser HD-451 and Sennheiser HD 400S, both models offer a strong combination of sound performance, comfort, and modern wireless features. Impedance levels vary (32 Ohms vs 18 ohm), which can affect compatibility and audio output when used with different devices. There is a noticeable difference in weight (380 g vs 217 Gm), which may affect comfort during extended use. Both models support modern Bluetooth connectivity, ensuring stable wireless performance with compatible devices.

Verdict: Choosing between Sennheiser HD-451 and Sennheiser HD 400S depends on whether you value better sound, longer battery life, or enhanced features.